1. Field of Invention
The present invention relates to a secondary pump for a brake and, more particularly, to an adjustor for a secondary pump of a brake.
2. Related Prior Art
A brake system of a car includes a brake pedal, a primary pump, four secondary pumps and four brakes. As the brake pedal is trodden, the primary pump is actuated. The primary pump transfers pressurized liquid to the secondary pumps. The secondary pumps actuate the brakes in order to stop the wheels of the car. Each brake includes a drum or disc and two brake shoes for rubbing against and stopping the drum or disc. This wears away the brake shoes so that the gaps between the drum or disc and the brake shoes get larger. The secondary pumps extend more in order to compensate the larger gaps. When the brake shoes are too thin for normal operation, they must be replaced with new ones. The secondary pumps must be pushed back to their original positions before such replacement can be conducted. Adjustors are used to this end.
Referring to FIGS. 1 and 2, a conventional adjustor includes a stationary plate 2, a dextrorotary threaded nut 3 or a levorotary threaded nut 3a attached to the stationary plate 2, a dextrorotary threaded bolt 1 or a levorotary threaded bolt 1a engaged with the dextrorotary threaded nut 3 or a levorotary threaded nut 3a, a pusher 4 for pushing a secondary pump 6, and a handle 5 operable in order to rotate the threaded bolt 1 or 1a. It is, however, exhausting to rotate the threaded bolt 1 or 1a. Moreover, it is inconvenient to keep both of the threaded bolts 1 and 1a, since the dextrorotary threaded nuts 3 are used in some cars, and the levorotary threaded nuts 3a are used in other cars.
Referring to FIG. 3, another conventional adjustor includes a stationary plate 11, a cylinder 10 attached to the stationary plate 11, a joint 16 connected to the cylinder 10, a lever 15 connected to the joint 16, a rod 12 extended through the cylinder 10 and connected to a piston (not shown) in the cylinder 10, a handle 14 operable in order to pull the rod 12, and a pusher 13 for contacting a secondary pump. The joint 16 can be connected to a pipe (not shown) that leads to a compressor (not shown). Pressured liquid can be transferred into the cylinder 10 in order to drive the piston and hence the rod 12. Since the cylinder 10 is not equipped with any release device, the pipe must be disengaged from the joint 16 before the handle 14 can be operated in order to pull the rod 12 back to its original position. This is, however, inconvenient.
The present invention is therefore intended to obviate or at least alleviate the problems encountered in the prior art.